[PATCH 10/19] Revert "ipc: add support for asynchronous callbacks"

[Eric Wong <e@80x24.org>]

This reverts commit a7e6a8cd68fb6d700337d8dbc7ee2c65ff3d2fc1.

It turns out to be unworkable in the face of multiple producer
processes, since the lock we make has no effect when calculating
pipe capacity.
---
 lib/PublicInbox/IPC.pm | 52 +++---------------------------------------
 t/ipc.t                | 25 --------------------
 2 files changed, 3 insertions(+), 74 deletions(-)

diff --git a/lib/PublicInbox/IPC.pm b/lib/PublicInbox/IPC.pm
index 3713b56b..7e5a0b16 100644
--- a/lib/PublicInbox/IPC.pm
+++ b/lib/PublicInbox/IPC.pm
@@ -18,7 +18,6 @@ use PublicInbox::OnDestroy;
 use PublicInbox::WQWorker;
 use Socket qw(AF_UNIX MSG_EOR SOCK_STREAM);
 my $SEQPACKET = eval { Socket::SOCK_SEQPACKET() }; # portable enough?
-use constant PIPE_BUF => $^O eq 'linux' ? 4096 : POSIX::_POSIX_PIPE_BUF();
 our @EXPORT_OK = qw(ipc_freeze ipc_thaw);
 my $WQ_MAX_WORKERS = 4096;
 my ($enc, $dec);
@@ -59,15 +58,10 @@ sub _get_rec ($) {
 	ipc_thaw($buf);
 }
 
-sub _pack_rec ($) {
-	my ($ref) = @_;
-	my $buf = ipc_freeze($ref);
-	length($buf) . "\n" . $buf;
-}
-
 sub _send_rec ($$) {
 	my ($w, $ref) = @_;
-	print $w _pack_rec($ref) or croak "print: $!";
+	my $buf = ipc_freeze($ref);
+	print $w length($buf), "\n", $buf or croak "print: $!";
 }
 
 sub ipc_return ($$$) {
@@ -188,21 +182,6 @@ sub ipc_lock_init {
 	$self->{-ipc_lock} //= bless { lock_path => $f }, 'PublicInbox::Lock'
 }
 
-sub ipc_async_wait ($$) {
-	my ($self, $max) = @_; # max == -1 to wait for all
-	my $aif = $self->{-async_inflight} or return;
-	my $r_res = $self->{-ipc_res} or die 'BUG: no ipc_res';
-	while (my ($sub, $bytes, $cb, $cb_arg) = splice(@$aif, 0, 4)) {
-		my $ret = _get_rec($r_res) //
-			die "no response on $sub (req.size=$bytes)";
-		$self->{-async_inflight_bytes} -= $bytes;
-
-		eval { $cb->($cb_arg, $ret) };
-		warn "E: $sub callback error: $@\n" if $@;
-		return if --$max == 0;
-	}
-}
-
 # call $self->$sub(@args), on a worker if ipc_worker_spawn was used
 sub ipc_do {
 	my ($self, $sub, @args) = @_;
@@ -210,8 +189,7 @@ sub ipc_do {
 		my $ipc_lock = $self->{-ipc_lock};
 		my $lock = $ipc_lock ? $ipc_lock->lock_for_scope : undef;
 		if (defined(wantarray)) {
-			my $r_res = $self->{-ipc_res} or die 'BUG: no ipc_res';
-			ipc_async_wait($self, -1);
+			my $r_res = $self->{-ipc_res} or die 'no ipc_res';
 			_send_rec($w_req, [ wantarray, $sub, @args ]);
 			my $ret = _get_rec($r_res) // die "no response on $sub";
 			die $$ret if ref($ret) eq 'PublicInbox::IPC::Die';
@@ -224,30 +202,6 @@ sub ipc_do {
 	}
 }
 
-sub ipc_async {
-	my ($self, $sub, $sub_args, $cb, $cb_arg) = @_;
-	if (my $w_req = $self->{-ipc_req}) { # run in worker
-		my $rec = _pack_rec([ 1, $sub, @$sub_args ]);
-		my $cur_bytes = \($self->{-async_inflight_bytes} //= 0);
-		while (($$cur_bytes + length($rec)) > PIPE_BUF) {
-			ipc_async_wait($self, 1);
-		}
-		my $ipc_lock = $self->{-ipc_lock};
-		my $lock = $ipc_lock ? $ipc_lock->lock_for_scope : undef;
-		print $w_req $rec or croak "print: $!";
-		$$cur_bytes += length($rec);
-		push @{$self->{-async_inflight}},
-				$sub, length($rec), $cb, $cb_arg;
-	} else {
-		my $ret = [ eval { $self->$sub(@$sub_args) } ];
-		if (my $exc = $@) {
-			$ret = ( bless(\$exc, 'PublicInbox::IPC::Die') );
-		}
-		eval { $cb->($cb_arg, $ret) };
-		warn "E: $sub callback error: $@\n" if $@;
-	}
-}
-
 # needed when there's multiple IPC workers and the parent forking
 # causes newer siblings to inherit older siblings sockets
 sub ipc_sibling_atfork_child {
diff --git a/t/ipc.t b/t/ipc.t
index 5801c760..face5726 100644
--- a/t/ipc.t
+++ b/t/ipc.t
@@ -37,7 +37,6 @@ my $ipc = bless {}, 'PublicInbox::IPC';
 my @t = qw(array scalar scalarref undef);
 my $test = sub {
 	my $x = shift;
-	my @res;
 	for my $type (@t) {
 		my $m = "test_$type";
 		my @ret = $ipc->ipc_do($m);
@@ -46,34 +45,10 @@ my $test = sub {
 
 		$ipc->ipc_do($m);
 
-		$ipc->ipc_async($m, [], sub { push @res, \@_ }, \$m);
-
 		my $ret = $ipc->ipc_do($m);
 		my $exp = $ipc->$m;
 		is_deeply($ret, $exp, "!wantarray $m $x");
-
-		is_deeply(\@res, [ [ \$m, \@exp ] ], "async $m $x");
-		@res = ();
 	}
-	$ipc->ipc_async_wait(-1);
-	is_deeply(\@res, [], 'no leftover results');
-	$ipc->ipc_async('test_die', ['die test'],
-			sub { push @res, \@_  }, 'die arg');
-	$ipc->ipc_async_wait(1);
-	is(scalar(@res), 1, 'only one result');
-	is(scalar(@{$res[0]}), 2, 'result has 2-element array');
-	is($res[0]->[0], 'die arg', 'got async die arg '.$x);
-	is(ref($res[0]->[1]), 'PublicInbox::IPC::Die',
-		"exception type $x");
-	{
-		my $nr = PublicInbox::IPC::PIPE_BUF();
-		my $count = 0;
-		my $cb = sub { ++$count };
-		$ipc->ipc_async('test_undef', [], $cb) for (1..$nr);
-		$ipc->ipc_async_wait(-1);
-		is($count, $nr, "$x async runs w/o deadlock");
-	}
-
 	my $ret = eval { $ipc->test_die('phail') };
 	my $exp = $@;
 	$ret = eval { $ipc->ipc_do('test_die', 'phail') };